Spinal implants and methods with extended multi-axial anchor assemblies

ABSTRACT

Systems and methods are provided that include a plate member engageable to the spinal column with an anchor assembly. The anchor assembly includes a coupling member having a post extending through at least one opening of the plate member and an anchor member pivotally captured in a receiver member of the coupling member below a lower surface of the plate member. A locking member secures the plate member to the coupling member. The coupling member includes an extended post with a proximal removable portion. The extended post facilitates placement of the plate member in position relative to the anchor assembly when engaged to the patient and be employed to reduce the plate member toward the anchor assembly when engaged to a vertebra.

BACKGROUND

In the art of orthopedic surgery, and particularly in spinal surgery, ithas long been known to affix an elongated member, such as a plate orrod, to bones in order to hold them and support them in a givenposition. For example, in a procedure to fuse damaged, diseased,malformed, or otherwise abnormal or injured vertebrae, the vertebrae arepositioned in a corrected position by a surgeon. An elongated plate isplaced adjacent to one or more vertebral bodies and bone anchors, suchas screws or bolts, are employed to secure the plate to the vertebralbodies. The anchors and plate are secured to each other to minimize orprevent relative movement. In this way, the vertebral bodies may be heldand/or supported in proper alignment for healing.

There remains a need for systems, devices and methods that facilitatepositioning and attachment of implants to one or more vertebrae of thespinal column, that provide various attachment modes of the plate to oneor more vertebrae of the spinal column, and that provide multi-axialcapabilities for the anchor assemblies employed in attaching the plateto one or more vertebrae of the spinal column.

SUMMARY

The present invention relates to orthopedic implant systems and methodsfor use in stabilizing bone members in a desired spatial relationship incorrecting bone misalignment disorders, to provide stabilization alongone or more vertebral levels, or for spinal or other bone fusion. Amulti-axial anchor assembly is engageable to an elongate implant member,such as a plate or rod member, to secure the implant member to a bonystructure.

According to one aspect, an anchor assembly is provided that includes ananchor member having a head and a lower portion extending from the headfor engagement with a bone member. The anchor assembly further includesa coupling member pivotally coupled to the head of the anchor. Thecoupling member includes a lower receiver portion defining an interiorreceptacle for receiving the head and a post extending from the receiverportion away from the head. The post includes a locking member mountingportion adjacent the receiver portion configured to engage a lockingmember and a removable extension portion extending proximally from themounting portion. The receiver portion defines at least one sidewallopening in communication with an exterior of the coupling member. Acrown is positioned in the receptacle of the coupling member about thehead of the anchor member. The crown includes a seating portionextending therefrom that is in communication with the at least onesidewall opening. The seating portion is positioned in contact with animplant member positioned about the post of the coupling member tosecure the implant member between the locking member and the seatingportion.

According to another aspect, a spinal plating system includes anelongate plate member including at least one opening extendingtherethrough between an upper surface and an opposite lower surface thatis positionable along the spinal column. The system further includes ananchor assembly engageable to the elongate plate member. The anchorassembly comprises a coupling member having a post positionable throughthe at least one opening and a receiver portion positionable along thelower surface of the plate member. The receiver portion includes areceptacle, and the post includes a mounting portion adjacent thereceiver portion and a removable extension portion extending proximallyfrom the mounting portion. The post further defines a passage extendingfrom a proximal end thereof to the receptacle. The anchor assemblyfurther comprises an anchor member including a head pivotally capturedin the receptacle of the receiver portion and a lower portion extendingfrom the head for engaging a bony structure of the spinal column. Alocking member is engageable to the mounting portion of the post incontact with the upper surface of the plate member to secure the platemember to the coupling member between the locking member and thereceiver portion.

According to another aspect, a spinal surgical method comprises:accessing at least one vertebra of the spinal column through anincision; engaging an anchor member of an anchor assembly to the atleast one vertebra through the incision, the anchor assembly including acoupling member pivotally mounted to the anchor member with a postextending proximally from anchor member; pivoting the coupling memberrelative to the engaged anchor member to orient the post in a desiredposition; positioning an elongate plate member about a proximal end ofthe post; advancing the plate member along the post to a locationadjacent the anchor member; engaging the plate member against a crown,the crown extending from the anchor in the coupling member to a locationoutside the post; and removing a proximal extension portion of the postafter engaging the plate member against the crown.

These and other aspects are discussed further below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a multi-axial anchor assembly.

FIG. 2 is an exploded elevational view of the anchor assembly of FIG. 1.

FIG. 3 is an assembled elevational view of the anchor assembly of FIG.1.

FIG. 4 is an assembled elevational view of the anchor assembly of FIG. 1rotated 90 degrees about its longitudinal axis from its FIG. 3orientation.

FIG. 5 is a top plan view of the anchor assembly of FIG. 4.

FIG. 6 is a sectional view of a coupling member comprising a portion ofthe anchor assembly of FIG. 1.

FIG. 7 is a sectional view of a crown comprising a portion of the anchorassembly of FIG. 1.

FIG. 8 is a perspective view of another embodiment crown.

FIG. 9 is a section view of another embodiment crown.

FIG. 10 is a section view of a locking member engageable to the couplingmember of the anchor assembly of FIG. 1.

FIG. 11 is a section view of a first embodiment anchor member of theanchor assembly of FIG. 1.

FIG. 12 is a sectional view of another embodiment anchor member of theanchor assembly of FIG. 1.

FIG. 13 is an elevational view of a plate member secured to themulti-axial anchor assembly of FIG. 1 with the locking member of FIG. 8,and with the plate member secured to an uni-axial anchor.

FIG. 14 is a sectional view through line 14-14 of FIG. 13.

FIG. 15 is a plan view of one embodiment plate member.

FIG. 16 is an elevational view of the plate member of FIG. 15.

FIG. 17 is a sectional view through line 17-17 of FIG. 16.

FIG. 18 is an elevational view of the plate member of FIG. 15 with acurved longitudinal profile.

FIG. 19 is a plan view of another embodiment plate member.

FIG. 20 is a plan view of another embodiment plate member.

FIG. 21 is a perspective view of another embodiment plate member with arod receiving portion.

FIG. 22A is an elevation view of an instrument for holding a platemember.

FIG. 22B is a top view of the instrument of FIG. 22A.

FIG. 22C is an enlarged view of a distal holding portion of theinstrument of FIG. 22A in a first orientation.

FIG. 22D is an elevation view of the instrument of FIG. 22A with theholding portion in a second orientation.

FIG. 22E is a top view of the instrument of FIG. 22A with the holdingportion in the second orientation.

FIG. 23 is an exploded elevation view of another embodiment multi-axialanchor assembly.

FIG. 24 is an elevational view of the anchor assembly of FIG. 23.

FIG. 25 is an elevational view of the anchor assembly of FIG. 24 rotated90 degrees about its longitudinal axis.

FIG. 26 is a sectional view of a coupling member comprising the anchorassembly of FIG. 23.

FIG. 27 is an exploded elevation view of another embodiment multi-axialanchor assembly.

FIG. 28 is an elevational view of the anchor assembly of FIG. 27.

FIG. 29 is an elevational view of the anchor assembly of FIG. 28 rotated90 degrees about its longitudinal axis.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustratedherein and specific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described processes, systems or devices, and any furtherapplications of the principles of the invention as described herein, arecontemplated as would normally occur to one skilled in the art to whichthe invention relates.

A multi-axial anchor assembly is provided to secure a plate member toone or more vertebrae of the spinal column. The anchor assembly includesan anchor member pivotally coupled in a receiver portion of the couplingmember. The coupling member includes a post extending proximally fromthe anchor member for receiving the plate member thereabout. The anchormember is pivotal relative to the plate when the post is positionedthrough an opening in the plate member. In one embodiment, the couplingmember can be engaged to the plate member such that the coupling memberis constrained from pivoting in at least one direction relative to theplate member while the anchor member is pivotal in the coupling member.

In one form, the coupling member includes a crown in the receiverportion that extends between the anchor and the plate member positionedabout the post. In one embodiment, the crown rigidly engages the anchormember in position relative to the coupling member and the plate memberwhen the locking member is secured against the plate member. In anotherform, the coupling member includes at least one window and the crownincludes a seat portion extending through the at least one window forcontact with a lower surface of the plate member positioned about thepost. The locking member firmly engages the plate member against theseat portion of the crown when the locking member is positioned againstthe upper surface of the plate member.

In another form, a multi-axial anchor assembly is provided that includesa coupling member for receiving a plate member thereabout and an anchormember extending distally of the coupling member. Before it is firmlyengaged to the plate member with a locking member, the coupling memberis received in an elongated slot of the plate such that is non-pivotaltransversely to a longitudinal axis of the slot while the anchor memberis pivotal in all direction relative to the coupling member. When thelocking member is secured to firmly engage the plate member to thecoupling member, the coupling member and the anchor member are fixedrelative to one another and relative to the plate member.

In another form, a multi-axial anchor assembly is provided that includesa coupling member and an anchor member pivotally mounted in a receiverportion of the coupling member. A post extends proximally from thereceiver portion, and receives a locking member to secure the platemember to the coupling member. The post includes a mounting portionadjacent the receiver portion to which the locking member is mounted tosecure the plate to the coupling member, and an extension portionextends proximally from the mounting portion to facilitate placement ofthe plate member about the post. The extension portion is removable fromthe mounting portion to minimize intrusion of the anchor assembly intoadjacent tissue post-operatively.

Referring now to FIGS. 1-5 there is shown a multi-axial anchor assembly20 having a first orientation aligned along longitudinal axis 21. Anchorassembly 20 includes a coupling member 30 and an anchor member 70pivotally engaged to coupling member 30 with a clip 60. Anchor member 70is pivotal about longitudinal axis 21 to a desired orientation relativethereto. A crown 50 is received in coupling member 30 adjacent anchormember 70, and includes at least seat portion that extends outwardlyfrom coupling member 30 through windows 48. Crown 50 is positionableagainst a lower surface of a plate member positioned about couplingmember 30, and a locking member 90 (FIG. 10) is engageable to couplingmember 30 to secure the plate member against crown 50, as shown in FIG.14. The downwardly or distally directed securing force supplied byengagement of locking member 90 can also seat crown 50 on anchor member70 to rigidly engage anchor member 70 in the desired position relativeto coupling member 30.

Further features of coupling member 30 will now be discussed withreference to FIGS. 1-6. Coupling member 30 includes a proximallyextending post 32 and a lower receiver portion 34 centered aboutlongitudinal axis 21. Post 32 includes a reduced size relative toreceiver portion 34 so that post 32 can pass through an opening of theplate member while at least a portion of the receiver portion 34 issized to prevent passage through the opening of the plate member. Asshown in FIG. 6, coupling member 30 includes an upper passage portion 42extending through post 32 in communication with a receptacle 44 definedin receiver portion 34. Receiver portion 34 includes an innercircumferential groove 46 adjacent receptacle 44 for receiving andretaining clip 60 therein.

Receiver portion 34 further includes at least one opening so that crown50 communicates with the exterior of coupling member 30. In theillustrated embodiment, coupling member 30 defines windows 48 inopposite sides thereof in communication with receptacle 44. As discussedfurther herein, at least a portion of crown 50 projects through windows48 for contact with a plate member positioned about post 32. Crown 50 issized to project outwardly from post 32 so that the plate memberpositioned thereabout will be supported by crown 50. Furthermore, asshown in FIG. 3, post 32 includes opposite flats 38 and opposite arcuatethreaded portions 40 extending therebetween. As discussed below andshown in FIG. 14, flats 38 engage the sides of an elongated slot orother opening in the plate member. In one embodiment, post 32 preventsthe plate member from twisting or rotating about post 32 by engaging thesides of an elongate slot of the plate. Threaded portions 40 threadinglyengaging a locking member 90 positioned about post 32.

Upper passage portion 42 of post 32 defines a proximally opening toolengaging passage 36 with internal surfaces forming a non-circularcross-section configured to engage a tool to facilitate rotatingcoupling member 30 about longitudinal axis 21. In addition, passageportion 42 can be sized to permit passage of a driving instrument toengage the anchor member captured in receiver portion 34 and apply adriving force directly to the anchor member through coupling member 30.

Referring now to FIG. 7, a sectional view of crown 50 is shown. Crown 50includes a seat portion 52 having arms 53 extending from a lower cupportion 54. As shown in FIG. 1, seat portion 52 forms an oval shape withlinear wall portions 57 extending between arms 53. Cup portion 54includes a semi-spherical shape projecting from seat portion 52 with anopening formed at its lower or distal end 55. Cup portion 54 defines areceptacle 58 having a concavely curved inner surface adapted to receivethe shape of the head of anchor member 70 positioned in coupling member30. A through-hole 56 extends through seat portion 52 and is incommunication with the receptacle 58 in cup portion 54, allowingplacement of a driving instrument therethrough for engagement with atool recess in the head of the anchor member 70 positioned in receptacle58.

FIG. 8 shows another embodiment crown 250 having an upper or proximalseat portion 252 and a lower or distal cup portion 254. Cup portion 254defines a receptacle which extends from seat portion 252 and opensdistally opposite seat portion 252. The head of the anchor member 70 isreceived in the receptacle defined by cup portion 254. At least aportion of seat portion 252 is formed by a pair of outwardly projectingarms 253 extending proximally and distally along cup portion 254. Athrough-hole 256 extends through seat portion 252 and is incommunication with the receptacle defined by cup portion 254.

FIG. 9 shows another embodiment crown 350, which is similar to crown 50.Crown 350 includes an upper or proximal seat portion 352, a lower ordistal cup portion 354 and a through-hole 356. Arms 353 extend outwardlyfrom cup portion 354, and include flange members 358 extending distallytherefrom at the outer ends of respective ones of the arms 353. Thedistal end of each flange member 358 includes inwardly facing lip 359.In use, lips 359 are supported on window ledges 49 of coupling member 30with the anchor member 70 pivotally captured in receiver portion 34.Flange members 358 and lips 359 maintain clearance between the head ofthe anchor member 70 positioned adjacent crown 350 so that when theplate member is secured against seat portion 352, flange members 358 andlips 359 maintain clearance between the head of the anchor member 70 andcrown 350 so that the anchor member 70 can pivot in coupling member 30.Crown 350 may be employed in situations where dynamic stabilization ofone or more vertebrae is desired. Dynamic stabilization can also beprovided by any one or combination of removing the ridges 82 from thehead 72 of the anchor member 70 (FIG. 11), providing a resilient crownmember, or maintaining separation between the crown member and the headof the anchor member.

FIG. 10 shows one embodiment of a locking member 90 engageable to post32 of coupling member 30. Locking member 90 includes a body 92 having asidewall 96 extending about a threaded through-bore 94. Through-bore 94extends along a longitudinal axis 95 that is alignable along thelongitudinal axis 21 of anchor assembly 20. A slot 98 extends throughsidewall 96 and is communication with through-bore 94, separatinglocking member 90 into proximal and distal portions 91, 93. When lockingmember 90 is engaged about post 32 and the distal portion is in contactwith the plate member 120, as shown in FIG. 14, further tightening oflocking member 90 against the plate member causes the proximal portion91 to deflect toward the distal portion 93. This provides aninterference fit or cross-threading between threads of post 32 and thethreads of locking member 90, preventing locking member 90 fromloosening in situ. Other embodiments contemplate other forms for lockingmembers 90, including a locking member without slot 98, a locking memberwith break-off portions to ensure proper torque is applied duringengagement, or a locking member providing other engagement relationshipswith post 32, such as a bayonet-lock, interference fit, or fusedconnection.

FIG. 11 shows one embodiment of anchor 70. Anchor 70 includes enlargedhead 72 at a proximal end thereof, and a distal portion that includes athreaded shaft 74 extending distally from head 72 to a tapered distaltip 78. Shaft 74 includes a thread profile 76 extending therealongconfigured to engage bony tissue. Shaft 74 and thread profile 76 mayinclude any suitable form, including flutes along all or a portion ofshaft 74, and uniform or varying thread pitches, thread heights, threadwidths, and shapes along shaft 74. Thread profile 76 can be configuredfor insertion into a drilled and tapped hole, can be configured as aself-tapping thread, or can be configured as a self-drilling andself-tapping thread. A non-threaded neck 80 is provided between head 72and shaft 74, although threads may extend along and/or run-out alongneck 80. Head 72 further includes a tool engaging recess 84 opening atthe proximal end thereof that can include any suitable configuration forreceiving a driving tool to apply a rotational driving force to anchormember 70 and threadingly engage it to bony tissue.

Head 72 includes plurality of ridges 82 extending circumferentiallytherearound adjacent the proximal end thereof, although a head 72without ridges 82 is also contemplated as discussed above. For example,dynamic stabilization of the spinal column segment can be provided withan anchor member having a smooth head that is allowed to rotate in crown50 when the anchor assembly is engaged to the plate member with lockingmember 90. Ridges 82, as discussed further herein, engage or bite intocrown 50 to lock anchor member 70 in position relative to couplingmember 30 when engaged to a plate member with locking member 90. Ridges82 can be formed by a series of flattened surfaces machined into head72. Other embodiments contemplate ridges 82 formed by spikes, knurlings,teeth, or other surface features. An anchor assembly 20 having an anchormember with ridges 82 provides a rigid or static connection between theplate member and the spinal column segment.

For any plate member, it can be entirely statically engaged to thespinal column with anchor assemblies 20 having anchor members that arerigidly engaged with the respective coupling member secured to the platemember. Any plate member can be entirely dynamically engaged to thespinal column with anchor assemblies 20 having anchor members that arepivotal in the respective coupling members secured to the plate member.Combinations of rigid and dynamic anchor assemblies 20 can be employedto engage a plate member to the spinal column.

Referring to FIG. 12, there is shown another embodiment of anchor 70 inwhich shaft 74 is provided with a lumen 86 extending longitudinallytherealong and opening at distal tip 78 and into tool engaging recess84. Lumen 86 can be configured to receive a guidewire or other guidingmember to guide placement of anchor 70 to the desired location relativeto the bony structure. Lumen 86 can also be employed to deliver bonegraft or other bone growth promoting and/or therapeutic material intothe bony structure in which anchor member 70 is engaged. Still otherembodiments contemplate shaft 74 including one or more fenestrations oropenings in communication with lumen 86 that are located between neck 80and distal tip 78.

Still other embodiment contemplate that anchor member 70 includes adistal portion with other configurations for engaging bony tissue. Forexample, the distal portion may include a cable, a hook, a clamp, astaple, a smooth shaft with wings or gulls, an expandable anchor, a bodyfor positioning in a disc space between vertebrae, or other structurefor engaging bony structure.

Referring now to FIG. 13, there is shown an elongate plate member 120engaged to vertebrae 24, 26 on opposite sides of disc space 28 with amulti-axial anchor assembly 20 and an uni-axial anchor 100. It should beunderstood that plate member 120 can be engaged to the vertebrae withany combination of multi-axial and/or uni-axial anchor assemblies.Uni-axial anchor assembly 100 includes a threaded shaft member 102 and aproximal head member 104 extending therefrom that is integrally formedtherewith. Proximal head member 104 extends through plate member 120,and includes a lower support member 108 against which the lower surfaceof plate member 120 is positioned. A locking member 106 is engaged tohead member 104 and clamps or seats plate member 120 against lowersupport member 108.

The connection of plate member 120 with multi-axial anchor assembly 20is also shown in section view in FIG. 14. Plate member 120 is positionedso that its lower surface is in contact at least partially with seatportion 152 of crown 150. Post 32 of coupling member 130 extends throughplate member 120, and locking member 90 is positioned about post 32. Aslocking member is advanced along post 32 toward the upper surface ofplate member 120, locking member 90 exerts a force against plate member120 and firmly secures it between seat portion 52 of crown 50 andlocking member 90. In the illustrated embodiment, the securing forcepushes crown 50 downwardly against head 72 of anchor 70. For embodimentscontemplating rigid fixation, the anchor member 70 includes ridges 82that bite into crown 50 to lock anchor member 70 in position relative tocoupling member 30 and plate member 120.

Referring now to FIGS. 15-17, further details of one embodiment of platemember 120 are shown. Plate member 120 includes an elongate body 122extending along a longitudinal axis 121. Body 122 includes at least oneopening in the form of an elongate slot 124 centered and extending alonglongitudinal axis 121. Slot 124 opens at upper and lower surfaces 125,127. Side rails 126 extend longitudinally along opposite sides of slot124, and end rails 128 extend between side rails 126 at the ends of body122.

Side rails 126 include an inner surface 129 extending along slot 124 andan outer surface 131. As shown in FIG. 17, body 122 includeslongitudinal grooves 130 in inner surface 129 extending along slot 124.The plate surfaces and edges of rails 126, 128 transitioning between theupper and lower plate surfaces and between the inner and outer railssurfaces can be rounded or chamfered to eliminate any sharp edges orabrupt transitions between plate surfaces.

In FIG. 18, there is shown plate member 120 with a curved profile alongits longitudinal axis 121. Upper surface 125 is concavely curved, andlower surface 127 is convexly curved. The curved configuration can beprovided by pre-bent plates, or by the surgeon bending the plate duringsurgery to provide the desire fit with the patient's anatomy.

In FIG. 19, there is shown another embodiment plate member 140. Platemember 140 is similar to plate member 120, and includes an elongatedbody 142 having opposite side rails 146 and opposite end rails 148.Plate member 140 includes openings in the form of a pair of elongatedslots 144, 145 are formed along body 142, and intermediate rail 150 islocated between slots 144, 145 and extends between side rails 146. Inthe illustrated embodiment, slot 144 is shorter than slot 145. Otherembodiments contemplate slots of equal length, and plate members withmore than two slots. For any of the plate member embodiments, the slotsmay include scallops, recesses or other features to facilitate placementor engagement of anchors therewith. It is also contemplated that theplate members may include two or more slots adjacent to and extendingalong one another. Still other embodiments contemplate the plates areprovided with openings between the upper and lower surfaces in the formof circular holes.

In FIG. 20 there is shown another embodiment plate member 160. Platemember 160 include a body member 162 having side rails 166 and end rails168. A pair of end slots 165 are provided adjacent end rails 168, and anintermediate slot 164 is provided between end slots 165 withintermediate rails 170 located between intermediate slot 164 andrespective ones of the end slots 165. In the illustrated embodiment,intermediate slot 164 is longer than end slots 165.

In FIG. 21 there is shown another embodiment plate member 180. Platemember 180 includes a body 182 having an anchor assembly engagingportion 184 and a rod receiving portion 188. Anchor assembly engagingportion 184 includes an opening therethrough in the form of an elongateslot 186 for receiving an anchor assembly, such as anchor assembly 20.Slot 186 allows the positioning of the plate member 180 to be adjustedby securing it thereto with anchor assembly 20. Rod receiving portion188 defines a passage 190 for receiving an elongate spinal rod 196therein. Passage 190 extends transversely to slot 186. In theillustrated embodiment, rod receiving portion 188 is a cylindricalmember that completely surrounds passage 190. However, other embodimentscontemplate a passage that is open along all or a portion of a sidethereof, a rod receiving portion 188 comprising multiple components forclamping or gripping the rod in passage 190, and other suitablearrangements for receiving and/or engaging a rod or other elongateimplant member.

FIGS. 22A-22E show one embodiment plate holder 200 engageable in, forexample, grooves 130 to hold the plate member for delivery to theoperative site. Examples of holding instruments are provided in U.S.patent application Ser. No. 10/202,918 filed on Jul. 25, 2002, which isincorporated herein by reference in its entirety. Plate holder 200includes a handle member 202 and a lever member 204 pivotally coupledthereto. A shaft member 206 is coupled to lever member 204 with a firstlink 208. A mounting shaft 212 extends through shaft member 206 fromhandle member 202, and includes a locking member 210 having a proximalknob portion and a shaft extending through mounting shaft 212, as shownin FIG. 22C.

The distal end of mounting shaft 212 includes a mounting member 214pivotally mounted thereto. Mounting member 214 includes an engagingportion 218 sized to fit within, for example, slot 124 of plate member120. Engaging portion 218 can also be sized to fit within an opening orslot of any plate member embodiment discussed herein. In the illustratedembodiments, engaging portion 218 includes engaging members 220 toengage groove 130 of plate member 120. Engaging members 220 can be inthe form of ball members or stems that can recess into engaging portion218 for positioning in slot 124, and can then be moved outwardly toengage groove 130 and mount plate member 120 to mounting member 214.Locking member 210 can then be rotated within mounting shaft 212 by itsproximal knob so that its distal end portion in engaging portion 218secures engaging members 220 in engagement with the plate member.

Shaft member 206 is movable relative to handle member 202 and mountingshaft 212 by moving lever 204 between an open position as shown in FIG.22A and a closed position as shown in FIG. 22D. Spring mechanism 222normally biases lever member 204 and handle member 202 to the openposition. In the open position, mounting member 214 is oriented so thatthe plate member extends along an axis 203 (FIG. 22C) which is orientedmore along the longitudinal axis 201 of instrument 200. In the closedposition, link 216 extending between shaft member 206 and mountingmember 214 pivots mounting member 214 about the distal end of mountingshaft 212 as shaft member 206 is moved proximally with lever 204. In theclosed position, axis 203 and thus the plate member secured to mountingmember 214 extend perpendicular to or substantially transversely to thelongitudinal axis 201 of instrument 200. Thus, instrument 200facilitates placement of the plate through narrow incisions or tubes byholding the plate in a first orientation that is oriented along theapproach to the spinal column and thereafter allowing the plate to beremotely pivoted into alignment along the spinal column.

Instrument 200 is just one example of a suitable instrument for holdingand delivering plate members to the spinal column for engagement theretowith the anchor assemblies discussed herein. Other examples of holdinginstruments include forceps or other grasping instruments, instrumentswith fasteners to engage the plate, and instruments that provide aninterference fit with the plate. The instruments can engage in the plateslots or holes, clamp between the outer surfaces of the plate, or holdthe plate between a slot or hole surface and an outer surface of theplate, for example. Still other examples contemplate the plate ismanually grasped and delivered to the surgical site.

Referring now to FIGS. 23-26, there is shown another embodimentmulti-axial anchor assembly 320. Anchor assembly 320 includes a couplingmember 330 with a post 332 extending along longitudinal axis 321 ofanchor assembly 320. Post 332 is extended proximally from a receiverportion 334 a sufficient length along longitudinal axis 321 tofacilitate positioning of a plate member about the coupling member 330and ease intra-operative assembly. Multi-axial anchor assembly 320 mayalso include post 332 having a removable proximal extension portion toprovide a low profile when implanted.

In the illustrated embodiment, anchor assembly 320 includes anchormember 70 that is pivotally captured in coupling member 330 with clip60. Crown 50 can be positioned in coupling member 330 about head 72 ofanchor member 70. Seat portion 52 of crown 50 is exposed through thecoupling member 330 so that a bottom surface of a plate member receivedover post 332 and positioned thereagainst can be secured to anchorassembly 320 with a locking member 90 as discussed above with respect toanchor assembly 20.

Coupling member 330 includes receiver portion 334 at a lower or distalend of post 332. Receiver portion 334 includes a receptacle 344 forreceiving head 72 of anchor member 70 therein, and an internalcircumferential groove 346 for receiving C-shaped clip 60. Clip 60pivotally supports head 72 in receptacle 344, and cup portion 54 ofcrown 50 is positioned in receptacle 344 about head 372 so that at leasta portion of seat portion 52 extends through opposite windows 348, asshown in FIG. 24.

Post 332 includes a locking member mounting portion 333 and an extensionportion 352 extending proximally from mounting portion 333. Extensionportion 352 provides a proximal extension of post 332 along longitudinalaxis 321 that facilitates placement of a plate member thereover and toguide the plate member to a location adjacent receiver portion 334 andcrown 50 during surgery. Also, extension portion 352 prevents the platemember from slipping off of post 332 as the plate and vertebrae aremanipulated during surgery and before engagement of the locking member90 to post 332. In addition, locking member 90 may be provisionallyengaged to post 332 about extension portion 352, allowing sufficientspace between crown 50 and locking member 90 for manipulating the platemember into position relative to anchor assembly 320 during surgeryprior to securement of the plate member to anchor assembly 320 withlocking member 90.

A break-off region 350 is provided between mounting portion 333 andextension portion 352. As shown in FIG. 26, break-off region 350 can beformed by inwardly tapering wall portions in post 332 that interrupt thethread profile along post 332 and also interrupt the surfaces formingflats 356 (FIG. 25.) A tool engaging passage 336 extends throughextension portion 352 and mounting portion 333, and includes toolengaging surfaces that define a non-circular cross-section. A gaugeportion 356 is provided in an inner wall surface of post 332 adjacentbreak-off region 350. Gauge portion 356 reduces the wall thickness ofpost 332 adjacent break-off region 350 so that a predetermined level oftorque applied to extension portion 352 in tool engaging passage 336proximally of break-off region 350 will sever extension portion 352 frommounting portion 333. The amount of torque required can be varied byvarying the thickness of the wall of post 332 at break-off region 350.

Extension portion 352 includes a tapered proximal end 358 to furtherfacilitate placement of the plate member thereabout. Extension portion352 includes opposite flats 356 and threaded arcuate portions 354extending between flats 356. Similarly, mounting portion 333 includesopposite flats 338 and threaded arcuate portions 340 extendingtherebetween aligned with the respective flats 356 and arcuate portions354 of extension portion 352. Threaded arcuate portions 340, 354threadingly receive and engage locking member 90 to post 332. Flats 338,356 are sized to abut the sidewalls along the elongate slot or otheropening of the plate member positioned thereover to eliminate lateralmovement or pivoting of the plate member. Coupling member 330 is furtheraligned relative to the opening of the plate member as the plate memberis advanced along extension portion 352. In another embodiment, it iscontemplated that post 332 is threaded along its entire length. In afurther embodiment, all or a portion of post 332 is provided withoutopposite flats, but rather includes a circular cross-section. In stillanother embodiment, post 332 is non-threaded along extension portion352.

Referring now to FIGS. 27-29, there is shown another embodimentmulti-axial anchor assembly 420. Anchor assembly 420 includes a couplingmember 430 with a post 432 extending along longitudinal axis 421 ofanchor assembly 420. Anchor assembly 420 can include any suitableconfiguration as discussed above with respect to the other embodimentanchor assemblies. Extended post 432 is similar to extended post 332 ofmulti-axial anchor assembly 320, but includes a length alonglongitudinal axis 421 such that its proximal end is positioned adjacentto or extends through the incision or opening provided to access thespinal column. Extended post 432 facilitates positioning of a platemember about the coupling member 430, and guides the plate memberthrough the incision to a location adjacent the vertebral body to whichanchor member 70 is engaged. Surgical instruments for holding the platecan be eliminated, reducing crowding in the operative space formed bythe incision.

In the illustrated embodiment, anchor assembly 420 includes an anchormember 70 that is pivotally captured in coupling member 430 with a clip60. A crown 50 can be positioned in coupling member 430 about head 72 ofanchor member 70. Seat portion 52 of crown 50 is exposed or extendsthrough coupling member 430 such that a lower surface of a plate membercan be secured thereagainst as discussed above with respect to anchorassembly 20.

Coupling member 430 includes a receiver portion 434 at a lower or distalend of post 432. Receiver portion 434 can be configured as discussedabove with respect to receiver portions 34 and 334. Post 432 includes alocking member mounting portion 433 and an extension portion 452extending proximally from mounting portion 433. A break-off region 450is provided between mounting portion 433 and extension portion 452.Extension portion 452 provides a proximal extension of post 432 thatfacilitates placement of a plate member thereover and to guide the platemember to a location adjacent crown 50 during surgery. Also, extensionportion 452 prevents the plate member from slipping off post 432 as theplate member and vertebrae are manipulated during surgery and beforeengagement of the locking member 90 to post 432. In addition, lockingmember 90 may be provisionally engaged to post 432 about extensionportion 452, allowing additional space for manipulating the plate intoposition relative to the anchor assemblies between crown 50 and lockingmember 90 during surgery and prior to securement of the plate member tothe anchor assembly with locking member 90.

Similar to anchor assembly 320, post 432 can be provided with aninternal tool recess (not shown) extending through extension portion 452and mounting portion 433, and a gauge portion in an inner wall surfacethereof adjacent break-off region 450 so that a predetermined level oftorque applied to extension portion 452 proximally of break-off region450 will sever extension portion 452 from mounting portion 433.

Extension portion 452 includes a tapered proximal end 458 to furtherfacilitate placement of the plate member thereabout. Extension portion452 includes opposite flats 456 and threaded arcuate portions 454extending between flats 456. Similarly, mounting portion 433 includesopposite flats 438 and threaded arcuate portions 440 extendingtherebetween. Threaded arcuate portions 440, 454 threadingly receive andengage locking member 90. Flats 438, 456 are sized to abut the sidewallsalong the elongate slot of other opening of the plate member positionedthereover to eliminate lateral movement or pivoting of the plate member,and to align coupling member 430 relative to the plate member.

Extension portion 452 can facilitate rotation of coupling member 430 sothat receiver portion 434 is properly aligned with the plate member.Rotation of coupling member 430 can result due to the tapered proximalend portion 458 receiving the plate member and self-aligning receiverportion 434 as the plate member is moved distally along extensionportion 452. Proximal end portion 458 can also be engaged by a tool ormanually to rotate receiver portion 434 into the desired positionrelative to the plate member.

For either embodiment of anchor assemblies 320, 420, posts 332, 432 canbe engaged by a reduction instrument to provide a mechanical advantagein positioning the plate member adjacent crown 50. Such reductioninstruments can reduce the displacement between misaligned vertebrae, orcan simply force the plate member into position adjacent the crown 50prior to final securement with locking member 90. Still otherembodiments contemplate that reduction of the plate and/or vertebrae canbe achieved by threading locking member 90 against the upper surface ofthe plate member to force the plate member adjacent crown 50.

For example, a plate member can be positioned about post 332, 432 andthe locking member can be provisionally engaged to the post 332, 432 sothat at a portion of the threaded arcuate portions 354, 454 are exposedproximally of the locking member. The reduction instrument can include afirst member threadingly engaged to extension portion 352, 452 and asecond member movable relative to the first member with an actuator. Thesecond member can be positioned into contact with the plate member, andleveraged off the first member with the actuator to move the platemember along the post 332, 432 toward crown 50. The locking member 90can then be advanced along the mounting portion 333, 433 to securelyengage the plate member against the crown member while the reductioninstrument holds the plate member in the desired position relative tothe anchor assembly.

In one embodiment, the plate member is sized to contact neighboringvertebrae, and includes at least one opening adjacent those vertebrae sothat the coupling member of the anchor assembly can be placed throughthe at least one opening when the anchor member of the anchor assemblyis engaged to the underlying bony structure. In another embodiment, theanchor assemblies can be provisionally captured on the plate member withlocking member 90 prior to engagement with the bony structure. The platemembers may also be sized and configured to extend across more than twovertebrae for multi-level stabilization procedures, or configured forengagement with a single vertebrae with a receiving member for receivingan elongate connecting element, such as a rod or plate, positionablealong two or more vertebrae.

The plate members can be pre-bent or bent during surgery to include acurvature, for example, to replicate or conform to a natural or desiredspinal curvature. It will be understood that any curvature appropriatefor one or more segments of the spine (whether cervical, thoracic,lumbar or sacral) could be incorporated into plate member. Suchcurvatures can include entirely convex, entirely concave, entirelystraight (i.e. essentially planar), and combinations thereof. It isfurther contemplated that the plate can be engaged to the anterior,oblique, lateral, or posterior bony portions of one or more vertebrae.

The illustrated embodiments of the plate members herein do not show aretaining member on or engageable to the plate member to prevent orresist backout of the locking member. However, the plate members may beprovided with one or more retaining elements to prevent backout of anyportion of the anchor assembly relative to the plate member. Theretaining elements may be any one or combination of a set screw, setscrew and washer, spring-loaded member, sliding washer or other similardevice attached to, captured on or integrally formed with the platemember.

For ease of use, a kit containing one or more of the parts of theimplant assembly may be provided. For example, a kit may include severalembodiments of plate members in several different lengths, sizes, slotconfigurations, and/or curvatures. Lengths or sizes appropriate forcervical, thoracic, lumbar and/or sacral implantation may be included.One or more sets of multi-axial and uni-axial anchor assemblies can beprovided with various anchor member sizes and coupling members adaptedfor attachment to one or more of the cervical, thoracic, lumbar andsacral regions of the spine may also be provided in such a kit. The kitmay further include multiple multi-axial anchor assemblies that includethose configured to provide rigid stabilization and dynamicstabilization of the spinal column when engaged to the plate member.

A method of using the multi-axial anchor assembly will now be described.The anchor assemblies can be employed in open surgical procedures whereskin and tissue is retracted, and in minimally invasive surgicalprocedures where the anchor assembly and/or plate members are positionedin the patient with one or more minimally invasive access approachesformed by micro-incisions, retractors, sleeves, and expanding sleeves.

In one procedure, a surgeon will make an incision into the patient at aplace relatively proximate to the vertebrae or other bone(s) to whichthe implant is to be attached. After the appropriate access to thesurgical site is obtained, a portion of the inferior vertebra to beinstrumented (e.g. the pedicle) is prepared in a standard manner. Forexample, an awl or drill may be used to prepare a hole, which is thenprobed for depth and tapped if appropriate for the anchor member. One ofthe anchor members is then inserted into the hole in the inferiorvertebra with a coupling member engaged thereto. Access to a portion ofthe superior vertebra (e.g. the pedicle) to be instrumented is thenobtained, either via the previous incision or via a separate incision.The point on the superior vertebra at which the implant is to beattached is identified, and the vertebra is prepared as described above.Another anchor assembly is engaged to the superior vertebra, and atleast one of the anchor assemblies is a multi-axial anchor assembly. Theat least one multi-axial anchor assembly can be configured to provideeither rigid or dynamic stabilization when engaged to the plate member,as discussed above. The process is repeated for any vertebrae betweenthe superior and inferior vertebrae if desired.

A plate member is then inserted directly through the incision or throughan access tube or retractor to the anchor assemblies. The post of eachof the at least one multi-axial anchor assembly coupling members ispositioned through or bottom-loaded through an opening of the platemember. The orientation and axial location of the coupling memberrelative to the anchor member and the plate member can be adjusted. Whenthe plate member and anchor assemblies are in the desired positionrelative to one another and the spinal column, locking member 90 can beadvanced to secure the respective anchor assembly and plate memberrelative to one another in the desired position. Prior to finallysecuring the plate member to the anchor assemblies, the vertebra can becompressed or distracted and maintained in this position with thesecured plate member. It is further contemplated that one or more discspaces or posterior elements between vertebrae can be fused with any oneor combination of bone graft, bone material, and implants. For anchorassemblies employing a coupling member with an extended post, theextension portion of the post can be removed after securement of theplate to the anchor assembly.

It will further be appreciated that the embodiments described aboveshould be made of materials suitable for implantation within the humanor other body, and may consist of inert metals like titanium orstainless steel. Other sturdy materials such as certain ceramics orplastics may also be considered. Bio-resorbable materials, such aspolylactic acid compounds, may be used along with or as a part of theparts described above. In one embodiment, a non-metal plate is employedwith the anchor assemblies. The engagement of the anchor assemblies tothe non-rigid plate includes at least some flexibility for flexiblespinal stabilization, allowing at least limited motion of theinstrumented vertebral level. Spinal motion can be enhanced by providinganchor assembly 20 in a form that dynamically engages the plate memberto the spinal column, as discussed above.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

1. An anchor assembly, comprising: an anchor member including a head and a lower portion extending from the head for engagement with a bone member; a coupling member pivotally coupled to said head of said anchor, said coupling member including a lower receiver portion defining an interior receptacle for receiving said head and a post extending from said lower receiver portion away from said head, said post including a locking member mounting portion adjacent said lower receiver portion configured to engage a locking member and a removable extension portion extending proximally from said mounting portion, wherein said post includes a break-off region between said locking member mounting portion and said removable extension portion, said break-off region interrupting an external thread profile that extends around said locking member mounting portion and said removable extension portion, said lower receiver portion defining at least one sidewall opening in communication with an exterior of said coupling member; and a crown positioned in said interior receptacle of said coupling member about said head of said anchor member, said crown including a seating portion extending therefrom, said seating portion extending through said at least one sidewall opening in direct contact with an implant member positioned around said post of said coupling member to secure the implant member between said locking member and said seating portion.
 2. The assembly of claim 1, wherein said post includes an internal passage extending along said longitudinal axis in communication with said interior receptacle of said lower receiver portion.
 3. The assembly of claim 2, wherein said internal passage is defined at least in part by tool engaging surfaces defining a non-circular cross-section along said internal passage.
 4. The assembly of claim 3, wherein said break-off region includes a gauge portion formed in an inner wall surface of said post along said internal passage.
 5. The assembly of claim 4, wherein said gauge portion interrupts said non-circular cross-section of said internal passage.
 6. The assembly of claim 4, wherein said break-off region further includes inwardly tapering outer wall surfaces adjacent said gauge portion.
 7. The assembly of claim 1, wherein said post includes a proximally tapered proximal end portion.
 8. The assembly of claim 1, wherein said post includes an internal passage extending through said locking member mounting portion and said removable extension portion.
 9. The assembly of claim 1, wherein said lower portion of said anchor member includes a threaded shaft.
 10. The assembly of claim 9, wherein said anchor member includes an unthreaded neck portion between said head and said dreaded shaft.
 11. The assembly of claim 10, further comprising a clip positioned about said neck portion and extending between said coupling member and said head, said clip being sized to prevent passage of said head therethrough to retain said anchor member in said coupling member.
 12. The assembly of claim 1, wherein said head includes a plurality of ridges extending thereabout oriented toward said crown.
 13. The assembly of claim 12, wherein said plurality of ridges engage said crown when the implant member is secured against said seating portion with said locking member, said engagement between said ridges and said crown preventing said anchor member from pivoting relative to said coupling member.
 14. The assembly of claim 1, wherein said seat portion of said crown includes arms extending therefrom and said at least one sidewall opening of said coupling member includes opposite windows, said arms being positioned through respective ones of said opposite windows.
 15. The assembly of claim 14, wherein said crown includes a cup portion extending from said seat portion, said cup portion including a receptacle for receiving said head of said anchor member therein.
 16. The assembly of claim 15, wherein said crown includes a through-hole extending through said seat portion into said receptacle of said cup portion.
 17. The assembly of claim 1, wherein said external thread profile threadingly receives said locking member thereabout.
 18. The assembly of claim 17, wherein said locking member includes a body having a wall extending about a central bore, said central bore receiving said post when said locking member is engaged thereto, said wall including a slot extending therethrough transversely to said bore in communication with said bore.
 19. The assembly of claim 1, wherein said post includes opposing flat surfaces extending along a length thereof interconnected by opposing arcuate threaded surfaces of said external thread profile.
 20. The assembly of claim 19, wherein said break-off region interrupts said opposing flat surfaces and said opposing arcuate threaded surfaces between said locking member mounting portion and said removable extension portion of said post.
 21. An anchor assembly, comprising: an anchor member including a head and a lower portion extending from the head for engagement with a bone member; a coupling member pivotally coupled to said head of said anchor, said coupling member including a lower receiver portion defining an interior receptacle for receiving said head and a post extending from said lower receiver portion away from said head, said post including a locking member mounting portion adjacent said lower receiver portion configured to engage a locking member and a removable extension portion extending proximally from said locking member mounting portion, wherein each of said locking member mounting portion and said removable extension portion include an external thread profile extending along a length thereof and an inner surface that extends around and defines an internal passage opening at a proximal end of said post and opening into said interior receptacle of said coupling member, said post further including a break-off region between said locking member mounting portion and said removable extension portion, said break-off region being formed by a gauge portion interrupting in said inner surface of said internal passage and forming a reduced wall thickness of said post at said break-off region, said lower receiver portion further defining at least one sidewall opening in communication with an exterior of said coupling member; and a crown positioned in said interior receptacle of said coupling member about said head of said anchor member, said crown including a seating portion extending therefrom, said seating portion extending through said at least one sidewall opening for positioning in direct contact with an implant member positioned around said post of said coupling member to secure the implant member between said locking member and said seating portion.
 22. The assembly a claim 21, wherein said internal passage is defined at least in part by tool engaging surfaces defining a non-circular cross-section along said internal passage.
 23. The assembly of claim 22, wherein said gauge portion interrupts said non-circular cross-section of said internal passage.
 24. The assembly of claim 21, wherein said break-off region further includes inwardly tapering outer wall surfaces aligned with said gauge portion, said inwardly tapering wall surfaces interrupting said external thread profile between said locking member mounting portion and said proximal extension portion.
 25. The assembly of claim 21, wherein said post includes approximately tapered proximal end portion.
 26. The assembly of claim 21, wherein said post includes opposing flat surfaces extending along a length thereof, said flat surfaces interrupting said external thread profile along said locking member mounting portion and said proximal extension portion.
 27. The assembly of claim 26, wherein said break-off region includes inwardly tapering surface extending into said post between said locking member mounting portion and said proximal extension portion, said inwardly tapering surfaces interrupting said opposing flat surfaces and said opposing arcuate threaded surfaces. 